Stroke is the leading cause of disability in the US. This disability is a consequence of, and a risk factor for, physical inactivity and stroke survivor, as a group, are extremely inactive. Most studies find that the average chronic stroke survivor is more inactive than even the most sedentary adults. Lack of physical activity has serious consequences in persons with stroke, including an increased risk of a second stroke, developing other diseases (i.e. diabetes) and mortality. The potential consequences of inactivity are even more alarming considering that inactivity gets worse over the first year after stroke. Therefore, left untreated, physical inactivity may be one of the most serious and costly sequela of stroke. Despite the severe consequences of inactivity after stroke, very little attention has been paid to whether activity is influenced by rehabilitation interventions for chronic stroke survivors. Nevertheless, one intervention that appears to hold promise for improving activity in chronic stroke survivors is fast treadmill training. However, even with the improvements observed after this intervention, the physical activity of the participants was still well below recommended levels. It is therefore imperative that interventions are developed to improve real-world physical activity in those with chronic stroke. In other populations, step activity monitorin programs have been shown to be extremely effective for increasing daily walking activity; however, their effectiveness has never been tested in chronic stroke survivors. The primary aim of this proposal is to test whether adding a step activity monitoring program to fast treadmill training can improve walking activity in chronic stroke survivors beyond improvements with fast treadmill training alone. The secondary aims will test whether this intervention also impacts walking speed, endurance and the energy cost of walking, all of which are known to be related to walking activity after stroke and are important measures of function. Using a randomized controlled experimental design, 40 chronic (> 6 months) stroke survivors, will receive either 12 weeks of fast treadmill training alone or 12 weeks of fast treadmill training in combination with a step activity monitoring program. The primary (physical activity) and secondary (walking speed, endurance, energy cost) outcomes will be assessed by blinded evaluators prior to initiating treatment (baseline), immediately after the last treatment (12 weeks post baseline) and 3 months after the last treatment (6 months post baseline). The expected positive effects of this novel intervention combining fast treadmill training and a step activity monitoring program on physical activity will provide strong support for the need to expand rehabilitation interventions t include features that facilitate an increase in the real-world physical activity of chronic stroke survivors.